Research And Implementation Of Undersampling Phase Detecting Method For Phased Laser Ranging

Phase laser rangefinder is widely used in space rendezvous and docking,aerospace,large-scale non cooperative target three-dimensional topography measurement and other fields in recent years,with the advantages of large measurement range,high precision and strong anti-interference ability,which is of great significance of the national defense construction and national economy of our country.At present,the phase laser ranging and phase discrimination system developed in China has many problems,such as high sampling frequency,poor phase discrimination performance,complex circuit design,etc.,which can not guarantee the high-precision measurement of the target.In view of the above problems,this paper proposes the under sampling full phase spectrum analysis phased discrimination method to improve the accuracy and stability of the system phase discrimination.On the premise of not losing the signal phase information,through the reduction of sampling frequency,the purpose of simplifying the system circuit and reducing the system design cost is achieved.At the same time,the under sampling phase discrimination system is designed based on FPGA,which can improve the speed of phase solution and provide theoretical and methodological basis of the development of high-speed,high-precision and low-cost laser rangefinder.The main research work of this paper is as follows:1.The key factors affecting the ranging accuracy is analyzed.Based on the analysis of the system structure and basic principle of single frequency and multi frequency ranging in phase laser ranging,the connection conditions between modulation frequencies of the condition of multi frequency ranging are given,and the key factors affecting the ranging accuracy is analyzed.2.An undersampling phase detection method of phase laser ranging is proposed.In this paper,an undersampling method is proposed to sample high-frequency signals,which can reduce the sampling frequency of the system,reduce the computing burden of the processor and reduce the hardware cost of the system on the premise of ensuring the measurement accuracy of the system.A phase discrimination method based on undersampling and full phase spectrum analysis is proposed to improve the phase discrimination accuracy and the anti-frequency shift performance of the system.3.An under-sampling phase detection system for phase laser ranging is designed.In order to improve the phase detection speed of the system and further verify the phase detection method proposed to this paper,an under-sampling phase detection system based on FPGA is designed.Mainly on the signal conditioning circuit,A/D converter sampling circuit,fpga-based phase discrimination circuit and arm-based data transmission circuit design.The phase detection system designed in this paper has a phase detection speed up to 1000 times per second,which can meet the requirement of phase detection of phase laser rangefinder at high speed.4.Experimental verification and error analysis.The functional test of each module and the phase discrimination accuracy test of the system is completed to verify the effectiveness of the under-sampling phased detection algorithm proposed to this paper.When the laser modulation frequency of the phase laser rangefinder is 40 MHz,the phase discrimination error of the measured system is within 0.1°,which can ensure the measurement accuracy of the phase laser rangefinder is millimeter.